At present, the magnetic materials are mainly composed of permanent magnetic materials and soft magnetIc materials. The magnetism of permanent magnetic materials can be preserved permanently, mainly including permanent magnetic materials and ferrite permanent magnets, represented by NdFeB.
The meaning of permanent magnetism is that (once magnetized) it can maintain a everlasting magnetism. Permanent magnetic materials is characterized by wide hysteresis loops, high coercivity and high remanence, it can be kept magnetized once they are magnetized. It is also called hard magnetic material. In practice, the permanent magnet material operates in the second quadrant demagnetization part of the hysteresis loop with deep magnetic saturation and magnetization. The commonly used permanent magnet materials are aluminum nickel cobalt series permanent magnet alloy, ferrochromium cobalt permanent magnet alloy, permanent magnet, rare earth permanent magnet material and composite permanent magnet material.
NdFeB (NdFeB) is the third generation rare earth permanent magnet, which consists of three rare earth elements, Nd, Fe and B. The proportion of neodymium element is in the ratio of 25%~35%, the iron element is 65%~75%, and the boron is about 1%. The raw materials used for ferrites are iron red, iron phosphorus, strontium carbonate and barium carbonate. These raw materials are all available and financially affordable. Nd-Fe-B has the advantage of high remanence density, high coercivity and high magnetic energy product. It is the most powerful magnetic material to date.
In terms of material prices, NdFeB is over 100 times more expensive than ferrite magnetic materials, and rare earth is a global strategic resource, and all countries in the world are scramble for it.